Potato digger chain and cover therefor



June 10, 1941. M. a. CRAWFORD POTATO BIGGER CHAIN AND COVER THEREFOR Filed Sept. 9. 1940 INVENTOR MA/Pco B. CRAWFORD Patented June 10, 1941 POTATO DIGGIR CHAIN AND COVER Marco 8. Crawford, Denver, 0010., assignor to The Gates Rubber Company, Denver, (iolo. a corporation of Colorado Application September 9, 1940, Serial No. 355,974

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This invention relates to improvements in potato disscr chains.

Where potatoes are raised in any considerable quantity for the market they are nearly always harvested by machinery and such machines are referred to as potato diggers."

The usual type of potato digger is provided with a conveyor chain formed from a plurality of links, each of which is a steel bar having its ends bent to form an interlock with an adjacent link, and in which the center portion forms a potato supporting means.

Potatoes when first removed from the ground are quite tender and bruise easily, with the result that a larse proportion of the potatoes are more or less bruised by their contact with the links of the chain.

It is the object of this invention to produce a tubular rubber covering for the potato supporting-portions of the links of the potato digger chain, which shall provide a yieldable resilient cushion about the metal of the links for the purpose of preventing injury to the potatoes during the digging operation.

Another object is to produce a tubular, resilient rubber composition covering for the links of potato digger chains which can be threaded over the link after the same has been formed and which will automatically center the tubular covering on the link rod.

A further object is to produce a rubber composition tube whose inside wall has means for centering and spacing it from the material of the k.

The above and any other objects that may become apparent as the description proceeds are attained by means of a construction and an arrangement of parts that will now be described in detail, and for this purpose references will be had to the accompanying drawing in which the invention has been illustrated, and in which:

Figure l is a view showing a shortsection of potato digger chain showing the resilient covering in place thereon;

Figure 2 is a section taken on line 2-2, Figure 8:

Figure 3 is a section taken on line 3-8, Figure 2;

Figure 4 is a section taken on line 4-4, Figure 5:

Figure 5 is a section, longitudinal and diametrical, taken on line 5-, Figure 4;

Figure 6 is a longitudinal section similar to that shown in Figure 5, but shows a modified form of construction;

Figure 7 is a section taken on line 1-1, Figure 6;

Figure 8 is a fragmentary transverse section similar to that shown in Figure 2, but showing the parts to an enlarged scale; and

Figure 9 is a fragmentary view of a link, showing the tube in the process of being applied thereto a tubular member II, which is preferably made from rubber so compoundedand cured as to be resilient and elastic. These tubes are secured to the straight portion of the link by means of cement in a manner which will be hereafter explained.

When links already formed are to be provided with resilient covering, the tubes must be of such size and construction that they can be threaded over the end of the link in the manner shown in Figure 9, and in order to make it possible to apply these protective tubes after the links have been bent in the manner shown, they must be of somewhat larger interior diameter than the outside diameter of the rod from which the link is constructed, because it is apparent that if they were to fit the rod closely the frictional resistance would be so great as to preclude the practicability of applying them. If the tube is made of sufliciently large inner diameter to permit it tobe readily applied, it is evident that after it has been positioned on the straight portion it will be very loose and will not retain its position. After the tube has been applied, or before it has been applied, the inner surface is ordinarily covered with a rubber cement, but where the tube has a smooth inner surface of a larger diameter than the rod forming the link, it will not be concentric with a link, and it has been found that under such circumstances the cementing is unsatisfactory and unreliable, and besides this, the eccentric position of the tube gives the finished link an unsymmetrical appearance.

As I have pointed out, it is the object of this invention to produce a tube having its inner sur ace provided with means for centering it on the ink so that it will assume a concentric relation after it has been positioned thereon.

Referring now more particularly to Figures 2, 4, 5, and 8, it will be obserted that that inner surface of the tube is provided with longitudinally extending ribs I4 that project inwardly to such an extent that they will engage the outer surface of the rod l and center the tube with respect to the rod. In the embodiments illustrated the ribshave been shown as spaced about 30 degrees, and since they are formed from resilient, elastic material they will readily bend so as to permit the tubeto be slipped over or applied to the links in the manner shown in Figure 9. Before the tube is applied to the link the inner surface is well covered with rubber cement that fills the spaces between the ribs, and after the tube has attained the position shown in Figure l, the resiliency of the ribs will cause them to as sume their normal position, thereby centering the tube and permitting the cement to set, whereupon the protective tube 'will be secured to the link in a concentric position.

For convenience in manufacturing, the centering projections are usually formed as longitudinally extending ribs, but this'is not essential as the centering can be effected by inwardly extending projections l5, as shown in Figures 6 and 'I. The exact shape of the centering projections is immaterial as they may perform their functions equally well if made in the shape shown, or inshapes diiferent'from those shown, and therefore, wheneverribs or projections are mentioned, applicant desires it to be understood that any mechanical equivalents of those shown and described can be employed.

Although the ribs are quite essential for the purpose of making it practical to apply the tubes to links already formed, they are also desirable where the tubes are applied to the links before the ends are bent, as, when ribs or other proiec tions are provided on the inner surface of the tube more space is provided for the cement and the latter becomes more uniformly distributed than would be the case-ii the inner surface were smooth and fitted the bar snugly.

If tubes having smooth inner surfaces of suiiiciently large diameter to permit them to be applied to the rod l0 are employed, it is impossible to center them on the supporting portions of the links. The tubular covering which forms the subject of this invention, as above described, have its inner surface provided with anguiarly spaced longitudinally extending ribs, or other projections. Such ribs or centering means require no great strengthv as they merely serve as spacers and by making them weak they do not appreciably add to the resistance offered in applying the tube to the link.

Coverings constructed as above described may be applied to the links either before or after they are formed and in either case the spacers serve to center .them and assure a uniform distribution of cement.

Having described the invention what is claimed as new is:

i. A potato digger chain, comprising links having central supporting sections, each having a tubular covering of resilient, yieldable, rubber composition, the tubular covering having its inner surface provided with a plurality oi angularly spaced, longitudinally extending ribs which engage the outer surface of the supporting scction of the link for spacing and centering the tube thereon.

2. A potato digger chain, comprising links having central supporting sections, each having a tubular covering of resilient, yieldable, rubber composition, the tubular covering having its inner surface provided with a plurality of spaced inwardly extending projections which engage the outer surface of the supporting section of the link for spacing and centering the tube thereon.

MARCO B. CRAWFORD. 

